The present invention relates to a control apparatus for an internal combustion engine such as a gasoline engine provided with feedback control of the air-fuel ratio and, more particularly, to an engine control apparatus which provides a correction of the fuel increment for acceleration and is suitable for an internal combustion engine of an automobile.
In general, automobiles are frequently subjected to acceleration and deceleration control during their operation. Therefore, as disclosed, for example, in Japanese Patent Laid--Open No. 58-144632, fuel injection control of an internal combustion engine for automobiles provides for correction of a fuel increment for acceleration, i.e. has an acceleration correction incorporated therein, so that the automobile will have a desired acceleration performance.
The Japanese Patent Laid-Open discloses an improvement in an electronic control fuel injection method wherein a basic fuel injection amount is obtained based on suction pipe pressure and the r.p.m. of the engine and, at a transition point, the fuel injection amount is determined by correcting the basic fuel injection amount according to the engine conditions. According to the improvement, a value is obtained by integrating an estimate preset according to the variation .DELTA.PM of the suction pipe pressure at each prescribed time and this value is used as a correction coefficient, and correction of fuel increment for acceleration is carried out using the correction coefficient according to an increase rate of the suction pipe pressure.
The above-mentioned conventional method, however, does not pay attention to whether or not the fuel increment amount added according to the prescribed condition, such as the suction pipe pressure variation, is proper. Therefore, there is no guarantee that an optimum acceleration performance is maintained at all times.